1. Field of the Invention
This invention relates to a question answering system, a data search method, and a computer program and more particularly to a question answering system, a data search method, and a computer program for making it possible to select and provide an appropriate answer by checking answer candidates using a check pattern in a system wherein the user enters a question sentence and an answer to the question is provided.
2. Description of the Related Art
Recently, network communications through the Internet, etc., have grown in use and various services have been provided through the network. One of the services through the network is search service. In the search service, for example, a search server receives a search request from a user terminal such as a personal computer or a mobile terminal connected to the network, executes a process responsive to the search request, and transmits the process result to the user terminal.
For example, to execute a search process through the Internet, the user accesses a Web site providing search service, enters search conditions such as a keyword, category, etc., in accordance with a menu presented by the Web site, and transmits the search conditions to a server. The server executes a process in accordance with the search conditions and displays the process result on the user terminal.
A data search process is implemented by various modes. For example, a keyword-based search system in which the user enters a keyword and list information of documents containing the entered keyword is presented to the user; a question answering system in which the user enters a question sentence and an answer to the question is provided; and the like are available. The question answering system is a system in which the user need not select a keyword and can receive only the answer to the question; it is widely used.
For example, JP 2002-132811 A discloses a typical question answering system. JP 2002-132811 A discloses a configuration for determining a search-word set and a question type from a question sentence, searching a document set stored in a document-set storage unit for a relevant-document set in accordance with the determined search-word set and the question type, extracting an answer to the question sentence from relevant documents, and providing the extracted answer and document information from which the answer is extracted as an answering result to the question sentence.
In a general question answering system, the question statement provided by the user is input and the answer to the question is output without outputting the whole hit document. Often, Web information is used as a knowledge source to obtain an answer. Under the present circumstances, however, it is difficult to say that the question answering system has sufficient answering accuracy, and the question answering system is less widespread than a general search system.
If a search is made using Web information of an enormous amount of data, the number of answer candidates acquired by making the search also is likely to increase. If a large number of such answer candidates contain the correct answer required by the user, the correct answer gets mixed with other erroneous answer candidates and it becomes difficult to select the correct answer; this is a problem.